Optimal design of an arch bridge with high performance steel for bridges using genetic algorithm

摘要

An optimal design of a steel arch bridge was performed in this study, to measure the effect of high performance steel for bridges (HSB), which was developed in Korea. A basic design was performed first, using SM520 only, which is a conventional rolled steel. Then, another steel arch bridge satisfying the same design requirement was designed using HSB only, which provided information for deciding on the proper shapes of cross section of various members. In the final stage, bridge members experiencing relatively high stress with respect to the yield stress, such as arch rib, main frame, and cross beam, were chosen to be made of HSB while other members were made of SM520. A genetic algorithm was used with the aims of minimizing the material cost of the major steel members. Limit stress and limit deflection were applied as constraints, according to the design specifications. By selectively choosing HSB, which has a relatively high allowable stress compared to general steel, it was concluded that the cross sectional area of the whole structure decreased and the material cost of the steel members also decreased, even considering the higher price per unit mass for HSB than that for SM520. To investigate the deterioration in dynamic performance due to the increased slenderness of steel members when HSB is used, an earthquake analysis was done. No meaningful change in the dynamic performance was found.